1. Field of the Invention
The invention relates to compositions comprising ionomers and polyamines or tertiary polyamides and articles such as golf balls and films containing the compositions.
2. Description of Related Art
Several patents and publications are cited in this description in order to more fully describe the state of the art to which this invention pertains. The entire disclosure of each of these patents and publications is incorporated by reference herein.
Golf balls and golf ball components may be formed from a variety of compositions, which provides a golf ball manufacturer the ability to alter the feel and aerodynamic characteristics of a particular ball.
For example, typical premium golf balls include wound balls, two-piece balls and multilayer balls. Wound balls typically have a spherical molded center, elastomeric thread-like material wound around the center, and either a thermoplastic or thermoset cover. “Two-piece” balls typically have a spherical molded core covered with a thermoplastic or thermoset material. “Multilayer” balls typically have a spherical molded core and one or more intermediate layers or mantles between the core and a thermoplastic or thermoset cover.
Golf ball covers formed from balata allow a highly skilled golfer to achieve spin rates sufficient to more precisely control ball direction and distance, particularly on shorter shots. Balata covered golf balls are easily damaged, however, which discourages the average golfer from using such balls. To remedy this durability issue, manufacturers have used ionomer resins as a cover material. Ionomers are copolymers of alpha olefins, particularly ethylene, and C3-8 α,β ethylenically unsaturated carboxylic acid, wherein the acid moieties of the copolymers are at least partially neutralized. U.S. Pat. No. 3,264,272 (Rees) teaches methods for making such ionomers from acid copolymers. A process for preparing the acid copolymers on which the ionomers are based is described in U.S. Pat. No. 4,351,931.
The degree of neutralization of the acid copolymer may vary over a wide range, and essentially any cation may be suitable as a counterion to the carboxylate groups in the ionomers. Typical cations include lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc, aluminum, and combinations of two or more of such cations. Neutralization of 90% of the carboxylic acid moieties in the acid copolymer, and higher levels of neutralization, including up to 100%, are known. These relatively high degrees of neutralization, however, may result in a loss of melt-processability or properties such as elongation and toughness. This factor increases in significance for copolymers with high acid levels.
While ionomer covered golf balls possess virtually cut-proof covers, their spin and feel may be inferior compared to balata covered balls. Polyurethanes and polyureas have also been recognized as useful materials for golf ball covers. Golf ball covers made of these materials have durability comparable to that of covers made from ionomer resins, but have the softer feel of a balata cover. Golf balls with a polyurethane or polyurea cover do not fully match ionomer resin golf balls with respect to the resilience or rebound of the golf ball cover, however. This property is in part a function of the initial velocity of a golf ball after impact with a golf club. Polyurethane and polyurea covers also have inferior moisture barrier properties compared to ionomer covers.
Ethylene acid copolymers neutralized by reaction with diamines are described in U.S. Pat. No. 3,471,460. A composition containing an ethylene/methacrylic acid copolymer neutralized by reaction with “N,N′-tetramethyl hexamethylene diamine”, with no metal cations, exhibited increased stiffness, compared to the non-neutralized acid copolymer, when measured according to ASTM D-747-58T.
An ionomer neutralized by reaction with a polyamine, preferably a diamine, that contains at least one R—CH2—NH2 group, and optionally partially neutralized with a base comprising a metal cation, is described in U.S. Pat. No. 4,732,944. This composition is used in films and glass laminates.
An ionomer composition comprising an ethylene acid copolymer neutralized by reaction with a “basic metal ion salt” and a compound comprising both an amine and a carboxylic acid in the same molecule is described in U.S. Patent Application Publication No. 2006/0014898. This composition is used in golf balls and sports equipment. The composition is reported to have a higher flex modulus than a comparative ionomer not containing the compound comprising both an amine and a carboxylic acid in the same molecule.
An ionomer composition having greater than about 70 percent of the acid groups neutralized by reaction with a neutralizing component including ammonium salts and/or monoamine salts is described in U.S. Pat. No. 7,160,954. This composition is used in golf balls. The composition is reported to have a lower flex modulus than a comparative ionomer not containing ammonium salts and/or monoamine salts.
Ionomer compositions neutralized by reaction with various amines are described in Journal of Applied Polymer Science, 1991, 42, 621-628. An ionomer composition neutralized by reaction with hexamethylene tetramine (HMT), a tertiary polyamine with molecular weight of 140 Da (Daltons), is reported to have a lower flex modulus than a comparative ionomer not containing HMT.
Japanese Patent No. 3540453 discloses an ionomer composition modified by the addition of H2N—[CH2RCH2NHCH2CH(OH)CH2NH]n—CH2RCH2NH2, wherein, R is a divalent alicycle or an aromatic hydrocarbon group, and 1≦n≦20. Japanese Patent Application JP1997-296082 discloses a similar composition wherein a condensed cyclic compound having two or more aminoalkyl groups is also present. Japanese Patent Application JP2005-263868 discloses an ionomer composition modified by a diamine compound wherein weight change begins at ≧150° C., as determined by a gravimetric method according to JIS K7120. An example of the amine is reported as “4 and 4-diamino-hexylmethane”, believed to be 4,4′-diaminodicyclohexylmethane.
It is desirable to provide a high performance material to be used in a structural layer of a golf ball, such as a cover, intermediate layer, core or center. In particular it is desirable to provide resins that have a balance of high coefficient of restitution (COR), high flex modulus, low moisture transmission, and good durability. It is also desirable that the compositions have melt properties suitable for injection molding, and in particular for injection molding in thin layers.